Method and apparatus for handling foaming and frothing liquids



Nov.3 1925- 1,560,286

W. D. MOUNT METHOD AND APPARATUS FOR HANDLING FOAMING AND FROTHINGLIQUIDS Filed March 1, 1924 avibentoz William 17. Mount v m8 61mmPatented Nov. 3; 1925.

UNITED STATES um n. noUmg-or nyucnnune, VIRGINIA,

IETHOD AND APPARATUS FOR HANDI-ING IOAMING AND FROTHING LIQ' UIDS.

Application filed March '1, 1924. Serial No. 696,407.

To all whom it may concern:

Be it known that I, WILLIAM D. MOUNT, a-citizen of the United States,residing at Lynchburg, in the county of Campbell and State of Virginia,have invented certain new and useful Improvements in Methods andApparatus for Handling Foaming and Frothing Liquids, of which thefollowing is a full, clear, and exact description.

This invention .relates to the handling of foaming and frothing liquids,and particularly to the handling of the hot digestor liquor in a pulpmill. The hot digestor liquor, after its separation from the pulp, has atendency to foam and froth to such an extent that it cannot be handledsatisfactorily by pumps, because the froth and foam spoils the vacuumcreated by the pump. It is practically impossible toarrange the variousapparatus of a mill in such a manner that pumps for the handling of thedigestor liquor may be eliminated. Accordingly, an

object of the invention is to provide an 1mproved method and apparatusfor the ban-- dling of foaming and frothing liquids, and the destructionof the foam and froth. A further object to provide an improved systemfor the washing of paper pulp and the handling of the filter liquortherefrom. A still further object is to provide improved apparatus foraccomplishing the above objects which will be exceptionally simple,effective, relatively inexpensive, and readily applicable to existingapparatus and systems used in pulpmills. Other objects and advantageswill be apparent from the following description of an embodiment of theinvention, andthe novel features will be particularly pointed outhereinafter in claims. I

o In the accompanying drawing a pulp separating and washing systemembodying the invention is illustrated.

In the illustrated apparatus, the pulp from the digestor is blown intopans or tanks in which it is diluted to the desired consistency. Thedilution is usually accomplished by the addition thereto of hot digestorliquor from which other pulp has been separated. This diluted pulp isthen conveyed to the stock or supply chest 1 from which it is withdrawnby a'pump 2 and circulated through a pipe 3 to the pan'4 of a filter orseparator, the overflow or surplus returning to the stock chest by areturn pipe 5. The filter or separator may be of any suitableconstruction but is preferably subject matter of my copendingapplication for patent Serial No. 636,365, filed May 3,

In this filter and Washer, the diluted pulp is circulated through thepan of the filter continuously to avoid the necessity of agitation inorder to keep the pulp fibres in suspension, the overflow returningthrough pipe 5 to the stock chest.

The rotary filter drum 6 is mounted for rotation so as'to dip partiallyinto the diluted pulp in the pan 4. As is well known, the drum isdivided into a plurality .of compartments which are connected insuccession to suitable suction devices for effecting the filteringoperation. In this type of filter or washer, a suction pipe 7 isconnected to the rotary drum 6 in such a manner that the suspending orfilter liquor passes therethrough as the cake is formed upon theperiphery of the drum, and this suction is continued through the portionof the drum periphery immersed in the. diluted pulp in the pan 4. Theliquid is drawn through the pipe 7 by suction from a source to bepresently explained.

A vacuum trap Sis provided with a lower or inlet chamber 9, anintermediate chamber 10, a steam belt 11, and an upper chamber 12. Theupper chamber 12 communicates with the intermediate chamber 10 bypassages 13 which pass through the steam belt 11. The steam beltcomprises a casing separated by end walls from the intermediate chamber10 and the upperchamber 12, to which steam is admitted by a pipe 14 andfrom which the condensation or drip is removed through a pipe 15. Thepassages 13 may conveniently be provided by tubes which are expandedinto the end Walls of the steam belt casing.

The-upper chamber 12 is connected by a pipe 16 to the upper end of acondenser'17, and the condenser, at its upper end but spaced from' theinlet from the pipe/16,

' circumference of the chamber 9. During the swirling of the digestorliquor, the foam or froth will be separated from the liquor bycentrifugal action, collecting in the central part of the chamber aroundthe axis of swirling, then will rise upwardly from the chamber 9 intothe intermediate chamber 10, and thence pass upwardly into the passages13.

As the foam or froth moves along the passages 13 the heat of the wallsof the passage will change the vapor tension of 7 the froth or foam sothat the bubbles will break and the froth and foam will be killed, allormost of it draining back down the tubes or passages and into the lowerchamber 9, and any of it which goes over the top of the tubes orpassages 13 will collect in an annular trough 20 in the upper chamber12, located below the upper ends of the tubes or passages 13. A mushroombattle 21 is mounted in the upper chamber 12 over the upper ends of thetubes or passages 13, so asto deflect-into the annular trough any of theliquid that may pass upwardly through the'tubes. The

baflie 21preferably has a small vent passage 22 therethrongh from itscenter, so as toprevent the formation of an air look under the baffle.

A pipe 23 opens into the lower chamber 9 centrally through thei' 'bottomwall. 24 thereof, and is connected to the inlet side of a strong liquorpump 25. A pipe 26 connected to the discharge side of thepump isconnected through valves 27 and 28 to pipes 29 and 30 which convey thestrong liquor to to a recovery plant or to the dilution tanks,

the disposition of the strong liquor depending upon whichplpf the valves27or 28 is open. A small c aiin pipe 31 connects the annular trough 20with the pipe 23 leading.

to the Suction side of the pump 25 so that any liquor collecting in theannular trough will be removed by the action of the pump.

A mushroom bafile 32 is disposed in the lower chamber 9'over the outletinto the pipe 23 and, in spaced relation to both the bottom and the sidewalls of the chamber, so that only the liquid from the periphery of thechamber may enter the pipe 23 running to the pump;

The liquor swirlingaround the periphery of the lower chamber will nothave any ma terial quantity .of froth or foam, and this liquid will passbeneath the bafile 32 and small vent 33 extending from its centralportion to approximately the lower end of the intermediate chamber 10 soas to prevent the formation of an air lock beneath the baflie.

In the washer 0r filter illustrated, the pulp cake or layer on the drumis subjected to two washings successively through spray devices 34: and35,-which are arranged above the drum so as to spray the filter cakesuccessively. The fresh water or washing fluid for the final wash isconducted through the pipe 36 to the second wash spray 35, from which itis sprayed upon the filter cake. This'sprayed liquid is drawn throughthe filte cake and drum and passes through the suction outlet 37 into awash trap 38. A pipe 39 connects the upper end of the wash trap 38 withthe pipe 16, so that the vacuum created in the pipe 16 by the exhauster19 u will be transmitted to the wash trap, and create a suction in thepipe 37 which draws the second spray water through the filter cake andthrough the drum. The wash water collecting in the trap 38 will passthrough the pipe 40 to the wash pump 11,- from which it is forcedthrough the pipe 42 into and through the first. wash spray device 34.This wash liquid is sprayed upon the newly formed filter cake andsubjects it to the first washing. v

The first wash liquid is drawn through the filter cake and through thedrum into the outlet pipe 43 leading to a second wash trap 44. The upperend of the wash trap 44 is connected by a pipe 45 to the pipe 39 whichruns to the pipe 16, so that. the vacuum created by the exhauster 19will be transmitted through the pipes 18, 16, 39 and 45 to the washtrap44, in whichit produces a suction in the pipe 43 and draws the firstwash liquid through the filter cake anddrum. This first wash liquid isconducted from the bottom of the trap through a pipe 46 to the pump 4",from which it is fo ced through a pipe 48 to the recovery plant.

In the operation'of this-apparatus the exhauster 19 creates a vacuum inthe pipe 18 which is transmitted to the condenser '17 and to the upperchamber 12 of the vacuum trap 8,-and the vacuum thus created in the trap8 produces a suction n-the pipe 7. At

be transmitted to the wash traps 3S and 44 the same time the vacuum inthe pipe 16 will so asto producea suction in the pipes 37 .and 43. Thestufli'jpump 2 is operated to circulate the diluted pu from the stockchest or dilution tank through the pan 4 of the filter. and washer, andback through the pipe 5. I v

The suction inthe' pipe;7 will draw the liquid carrying the pulp insuspension through the sieve-like periphery of the drum 6, which causesthe formation of the filter cake upon the portion ofthe periphcry of thefilter drum which is immersed -in the liquid in the .pan 4. The digestoror filter liquor will be conducted through the pipe 7 into the lowerchamber 9 of th e trap dlscharging it in a direction approxiuidwithoutthe foam, will be drawn through mately tangential to the chamber,and in entering the chamber in he," manner the liquor .will swirl aroundthe lateral wall of the chamber with the result that the liquid will bycentrifugal action, remain around the lateral wall .of the chambenandthe froth or 'foam carried thereby will collectin into the. annulartrough and drained through the pipe 31- into the inlet pipe 23 leadingto the strong liquor pump. The liqpipe 23 to the pump 25 and then forcedto the diluting tanks, or-to the recovery plants where the chemicalscarried thereby ,are re moved or recovered. I

The drum 6 isrotated by any suitable source of power, the cake or layerofpulp formed thereon passing successively under the spray from thedevices 34 arid 35, and after being washed the cake of pulp will.beremoved in any suitable manner such as by the sdraper or doctor blade49. The washed pulp removed in this manner, drops, or is conveyed into/astock chest where clean water is added, and the water and pulp mixtureis then'delivered to the screens, or to the Jordan mills for treatment,preliminary to bleaching or delivery 'to the'paper machines.

The layer of pulp upon the drum is sprayed by fresh water :or washingliquid from the spray device 35, and the spray is drawn through the drumand the pipe 37. into the trap 38, from which it is Withdrawn and forcedby the. pump 41 through c the spray device 34 to give the pulp itsinitial washing. The first wash liquid from the device 34 is drawnthrough the cake or layer of pulp, and through the pipe 43 into the trap44 from which it is withdrawn and forced by the pump 47 through the pipe.48 to the recoyery plant. Any moisture or vapor'in the traps 38 or 44and the upper chamber 12 of the vacuum trap 8', which is carried overinto the condenser 17, will be condensed therein and drain through apipe 50 into a hot well 51 and thence into a sewer d1 disposal device52.

- Itwill be observed that with this apparatus, the strong liquor fromthe filter and washer is handled efi'ectively, and the foam and froth iskilled so as not to interfere with the action of the strong liquor pumpor pass over to the exhauster which provides the suction for the strongliquor pipe 7.

connecting the various parts of the apparatus in the mannerdisclosed,the only additional apparatus necessary will be the vacuum trap 8v forkilling the froth and foam in the strong digestor liquor coming from thefilter and washer, and such a trap is readily applicable to existingpulp handling appa- Ihtus and systems.

It will be understood that by the use of the term vacuum throughout thespecification and claims, Lmean in effect a partial vacuum, since it isimpossible in practice to produce a'perfect vacuum. It will also be un-'derstood that. while I have described a method and apparatus for killingthe froth and foam as applied to the strong filter liquid in the pulpwashing industry, in which application it has great value, it will beunderstood that it maybe used equally well for killing the froth andfoam of other liquids. The vacuum trap 8 may also be connected in commonto any number of filters and washers.

The washer or filter is referably located 30 feet or over above t elower or inlet chamber 9 of,the trap 8:50 that when the filtering actionis ones started by thevacuum in the chamber 9, that-falling head ofliquor in the pipe 7 will produce a'si honing aceon which'will continueto pul the liquor through the filter drum 6 from the pan 4- of thewasher. Consequently there will be less tendency for the strongsulphateliquor to foam or froth, than would be the case where the vacuumwas depended upon continuously. The washer is constructed to cut offcommunication of the various filter sections with the pipe 7 as soon asthe sections emerge from the liquid in the pan 4, so as to prevent asfar as possible the entrance of air into, the pipe 7 because air. in,the liquortends to induce foaming and frothing. Since the suction frompipe43 may be communicated to the sections of the filterimmediatelyafter they are. disconnected from pipe 7 there can be no cake or pulplayer uponthe falling ofi prematurely.

It will be-obvious that various changes in the details andarrangeme'ntsof parts,

drum periphery danger of the filter herein described and illustrated forthe purpose of explaining the nature of the'invention, may be made bythose skilled in the.

art within'the principle and scope of the invention as expressed in theappended claims.

I claim:

1. A vacuum trap comprising a casing having upper and lower chambersconnected by a heated passage, means for introducing the liquid to betreated into the lowerchamber approximately tangentially thereof tocause a swirling of the introduced liquid, a pump connected at itssuction side to the bottom of the lower chamber for removing the body ofthe liquid, any foam and froth created and rising through the heatedpassage being brokenmp by theheat.

2. A vacuum trap comprising a casing having an inlet'cham'ber and aheated section communicating with the upper part of the inlet: chamber,means for admitting the liquid to be treated to the inlet chamber in a.direction approximately tangentially of,

the chamber whereby the entering liquid will swirl around the chamberand the froth and foam created will collect in the center and rise intothe heated section where the bubbles tion communicating with the upperpart of the inlet chamber, means for admitting the l quid to be treatedto the inlet chamber in a direction approximately tangentially of thechamber whereby the entering liquid will swirl around the chamber andthe froth and foam created will collect in the centertion to the chamberand spaced from the lateral wall whereby only the liquid from theouterand lower part of the chamber may pass to the pump.

4 4. A vacuum trap comprising a casing having an inlet chamber and aheated section communicating with the upper part of the inlet chamber,means for admitting the hquid'to be treated to the inlet chamber in adirection approximately tangentially of the chamber whereby the enteringliquid.

will swirl around the chamber and the froth and foam created willcollect in the center and rise into the heated section where the bubbleswill bebroken up by the heat, the

liquid running back into the chamber, a

pump connected at its suction side to the ottom of the chamber centrallythereof, and a baflle wall disposed in spaced relation to the bottomwall over the pump connec-' tion to. the chamber and spaced from thelateral wall whereby only the liquid from and rise into the heatedsection where the bubbles will be broken up b the heat, the liquidrunning back into t e, chamber, a pump connected at its suction side tothe bottom of the chamber centrally thereof,

and a mushroom baflie wall disposed in spaced relation to the bottomwall over the pump connection to the chamber and spaced from the lateralwall whereby only the liquid from the outer and lower part of thechamber may pass to the pump, said bafile wall having a small vent pipeleading from substantially the highest part of the .batlle wallto-prevent the formation of an air lock under the bafile wall.

6. A vacuum trap comprising a casing havin an inlet chamber in the lowerpart and a heati'ng chamber above the. inlet chamber, said heatingchamber having a passage therethrough and communicatin at one end withthe inlet chamber, means for creating a vacuum connected to the otherend of the passage, means for introducing the liquid to be treated intothe inlet. chamber in a direction approximately tangentially thereof tocause a circumferential swirling of the introduced 11 uid, and suctionmeans for withdrawing t e liquid from the inlet cham- -ber at a point'ecc'entrically, of the axis of swirling, whereby the non-frothin andnonfoaming liquid will be drawn 0 and the foam and froth dollecting inand rising from the center of the swirling liquid will enter the passageand be brolten up by the action of the heat.

7. A vacuum trap comprising a casing having an inlet chamber in thelowerpart and ra heating-chamber .above the inlet chamber, said heatingchamber having a passage therethrou hand. cdmmunicating at one end withthe inlet chamber, means for creating a vacuum connected to the otherend of the passage, means" for introducing the-liquid. t be treated intothe inlet chamber in a direction approxim ly tangentially thereof tocause a cir inferential swirling of the introduced liquid, suction meansfor withdrawing the liquid from the inlet chamber centrally at thebottom thereof, and a bafiie wall in the inlet chamher, over the outletto the suction meansin spaced relation; to the bottomand lateral wallswhereby the non-frothing and nonfoaming liquid will be drawn ofi'v fromthe outer edge of the bottom of the inletchamher, and vthe foam andfroth collecting in and rising from the center of the swirling liquid.will enter the passage and be broken up by the action of the heat.

8. A vacuum trap comprising a casing having an inlet chamber in thelower part and a heatingchamber above the inlet chamber, said heatingchamber having a passage therethrough and communicating at one endwiththe inlet chamber, means for creating a vacuum connected to theother end of the passage, means for introducing the liquid to be treatedinto the inlet chamber in a direction approximately tangentially there rof to cause a circumferential swirling of the introduced li uid, suctionmeans for withdrawing the iquid from the inlet chamber centrally at thebottom thereof, and a mush- I room bafile wall in the i let chamber overthe outlet to the 'suctio means in spaced relation to the bottom andlateral wallswhereby the non-frothin and non-foaming liquid will bedrawn ofl' rom the outer edge of the bottom of the inlet chamber, andthe foam and froth collecting in and risin from the centerof'theswirlingliquid wil enter the passage and be broken up by theaction of the heat, said bafiie wall having a vent therein to preventtheformation of an air lock thereunder.- A

'9. A vacuum trap com rising a casing having upper and lower 0 ambersconnected by a passage, means by which the assage may be heated, abaflle over the en of the passage entering the upper-chamber, a dripconduit for removing any s it-over from the passage into said upper camber, means by whichawa'cuum may be created in the upper chamber, aliquid inlet confor connection to the inlet side of a hereby thefrothand foam in the 11am;

duit opening into the lower' chamber in a direction approximatelytangentially of the chamber to cause a swirling of the liquid enteringthe lower chamber, and an outlet from the bottom wall of the lowerchamber pump,

uced liquid, will, by reason of the swirl ing movement, collect in thecenter and rise having upper and lower "chambers connectfrom theswirling liquid, and entering said passage will be broken up by the.heat.

10. A vac trap comprising a casing ed by a passage, means by which theassage may be heated, abafiie over the en of the ,passa e entering theupper chamber, a drip con uitfor removing any splt over from the passageinto said upper chamber, means by which a vacuum may be created in theuper chamber, a liquid inlet conduit opening into the lower chamber in adirection approximately tangentially of the chamber to cause a swirlingof the liquid entering the lower chamber, an outlet from the bottom wallof the lower chamber for connection tothe inlet side of apump, wherebythe froth and foam in the introduced liquid will, by reason of theswirling movement, collect in the center and rise from the swirlingliquid, and entering said passage will be broken up by the heat, and asecond bafile in the lower chamber over the outlet whereby the liquidwithdrawn will'be taken. from the swirling part which is without foam.

11. A vacuum trap comprising a casing having upper and lower'chambersconnected by a passage, means by which the passage may be heated, abaflle over the end of the passa e entering the upper chamber, a 'dripcon uit for removing any s it-over .from the passage into said upper camber, means by which a vacuum may becreated v in the upper chamber, aliquid inlet conduit opening into the lower chamber in adirectionapproximately tangentially of the chamberto cause a swirling of theliquid entering the lower chamber, an outlet from the bottom wall of thelower chamber. for connection to the inlet side of a pump, whereby thefroth and,foam in the -intro-' duced liquid will, by reason of theswirling movement, collect in the center and rise from the swirlingliquid, and entering said passage will be broken up by the heat, and

without foam,'said' baflies both having vents '-therethrou h to reventthe formation of air lockstereun er. a

12. A vacuum trap comprising a casing having upper and lower chambersconnected vby a passage, means by which the passage may be heated, abaflie over the end of the passage entering the upper chamber, a dripconduit for removing any s it-over from the passa e into said uppercamber, means by whicfi' a vacuum may be created in the upper chamber, aliquid mlet conduit opening intothe lower chamber in a direc t1onapproximately tangentially of the chamber .to cause raswirling of theliquid entering the lower chamber, an

outlet from the bottom ,wall of the lower chamber "for connection. tothe inlet sideof a pump, whereby the froth and foam in the introducedliquid will, by reason of the swirling movement, .collect in the centerand'rise fromthe swirling liquid, and

entering said passage willbe broken up by chamber over the outletwherebythe liquid withdrawn will be taken from. the swirling )art which iswithout foam, said bafiles 0th having vents therethrough to prevent 5the formation of air locks thereunder, the

Vent from ing liquid.

13. The

the battle in the lower chamber method of handling strong digestorliquor which comprises causing a swirling of the liquor to centrifugallyseparate the foam and froth from the liquid, and heating the froth andfoam rising from the swirling liquor to break the bubblesfby a change intheir vapor tension. 7

In Witness whereof I hereunto subscribe my signature.

- WILLIAM D. MOUNT.

